The present invention relates to methods and apparatus for chromatic dispersion compensation, and particularly for such compensation using an etalon, such as a Gires-Tournois etalon.
This invention provides chromatic dispersion compensation and apparatus that is effective over a wide range (such as from 0 km to about 100 km of SMF-28 fiber, which is equivalent to 0 to about 1700 picoseconds per nanometer) and that can reduce the bit error rate (hereinafter, xe2x80x9cBERxe2x80x9d) for a known optical signal to noise ratio (hereinafter, xe2x80x9cOSNRxe2x80x9d), even when compared to the case where the transmitter and receiver are positioned back-to-back.
According to the invention, a notch filter is combined with any type of chromatic dispersion compensator. The notch filter can be integrated into an existing compensator component or added, as desired.
There are a number of possible approaches according to this invention. As explained more fully below, a chromatic dispersion compensator can include an etalon, such as a Gires-Tournois (hereinafter, a xe2x80x9cGTExe2x80x9d) etalon. In one approach, the GTE is thermally tuned. Alternatively, the GTE can be electrically tuned. The invention can also be, used with devices that are not etalon-based, such as fiber Bragg grating-based devices. In yet another approach, the GTE can be entirely passive, such as by using an air gap with a low expansion spacer. Thus, it is not necessary to actively tune the GTE using a fixed optimal configuration.